Tires with high strength reinforcement

ABSTRACT

A strip of tire ply stock is reinforced with steel cords wherein the steel cords are constructed of high strength wire filament having at least a tensile strength of -2000xD+4400 MPa where D is the filament diameter in mm. Tires are constructed with the ply stock in the belt and/or carcass.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a Continuation application of application Ser. No. 08/768,152,filed on Dec. 17, 1996, now U.S. Pat. No. 6,247,514, which is acontinuation-in-part of application Ser. Nos. 08/514,081, and08/514,080, both filed on Aug. 11, 1995, both now abandoned, which weredivisional Applications of application Ser. No. 08/360,973, filed Dec.20, 1994, now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to cord, cord reinforced plies and radialtires for vehicles. Radial tires are those tires wherein the cords ofthe carcass plies, which extend from one bead to the other, liesubstantially on radial planes. More particularly, the present inventionrelates to a structure of one or more plies formed of a cord reinforcedcomposite having rubber where preferably the structure is for tires,such as for a tire carcass or a tire belt wherein at least one of theplies in the carcass or belt has the cords therein biased with respectto the direction of rotation of the tire.

SUMMARY OF THE INVENTION

Reinforced elastomeric articles are well known in the art. For example,conveyor or like type belts, tires, etc., are constructed with cords oftextile and/or fine steel wire filaments or strands. In particular,belts used in pneumatic tires are constructed of up to eight ply layerswith the cord reinforcement of adjacent plies being biased with respectto the direction of movement of the tire where it is desired toreinforce in both the lateral direction and the direction of rotation ofthe tire. Further, cords made of strands of multi-twisted filaments offine wire with a single strand construction having two or more filamentsand a wrap filament thereabout to reinforce the cord structure have alsobeen known. In some cases, the reinforcement includes the use of singlestrand cords of multi-filaments which are not twisted about each otherbut rather twisted altogether as a bundle or bunch (bunched cord) tosimplify the cord construction, as disclosed in assignees's U.S. Pat.No. 4,947,636 which is incorporated by reference in its entirety herein.Higher fatigue life requirements for composites in tires have resultedin cords with smaller filament diameter requiring more filaments in thecord to obtain the necessary strength.

Two ply tire belts for passenger and light truck tires can have cords of2×0.255ST and 2+2×0.32-0.40ST, respectively. An example of the firstconstruction is described in Assignee's Statutory Invention RegistrationH1333, issued Jul. 5, 1994, which application is incorporated byreference in its entirety herein, wherein multi-filament cords such as2×0.255ST are disclosed. This designation means one cord of two (2)0.255 mm. diameter filaments. An example of the 2+2×0.32-0.40ST cord isdisclosed in Assignee's U.S. Pat. No. 5,242,001, which is incorporatedin its entirety by reference herein. This designation means one cord offour (4) 0.32-0.40 mm. diameter filaments (with two (2) filamentstwisted at a shorter lay length than the other two (2) filaments).Multi-filament cords such as 2+2×0.32-0.40ST have been found necessaryto meet the higher demand of strength for composites in tire belts,typically used in light truck applications. Both of these cords weremade of super tensile (ST) steel as defined hereinafter. Though corddesigns incorporating super tensile (ST) steel have proven effective,there is a continuing need to develop lighter weight cord constructionswith improved characteristics, such as higher corrosion propagationresistance and improved tire performance, over recent high tensile andsuper tensile constructions.

The described cord constructions generally have not found use in largertires, such as off-the-road (OTR) tires, because they were not strongenough. Even with the advent of high tensile filament such as inAssignee's 2+2× cord, disclosed for use in passenger and light trucktires, the large OTR tires continue to use traditional constructionssuch as 7×7×0.25+1HT and 3×7×0.22HE comprising seven strands each ofseven 0.25 mm diameter high tensile filaments that are twisted togetherand spiral-wrapped; and three strands each of seven 0.22 mm diameterhigh tensile filaments that are twisted together, respectively. Thesteel cord cable currently used for ply reinforcement in OTR tires forsizes 36.00R51 and larger is stranded cord of high tensile tire cordfilament such as 7×19×0.20+1HT cord comprising seven strands each ofnineteen 0.20 mm diameter high tensile filaments that are twistedtogether and spiral-wrapped. These cords were made of high tensile (HT)steel as defined hereinafter.

More recently, OTR tires can be constructed of multiple plies belts orsingle ply with reinforcing cords such as 27×0.265ST or 5+8+14×0.265ST+1as disclosed in Assignee's U.S. Pat. No. 5,318,643 which patent isincorporated by reference in its entirety herein. Still, current steelcord constructions have breaking load and cable gauge limitationspreventing the needed design inch-strength from being achieved for tireslarger than 40.00R57 used on trucks and earthmovers weighing up to andsometimes more than 320 tons. In addition, there is a need to increasethe rivet area in the ply and belt, i.e., the space between the cords,for tire sizes of 36.00R51 and larger so that more rubber can penetratebetween the cords during tire manufacture to enhance the quality ofcalendered treatment by preventing “weak rivet” or “loose coat” (whichcan result in trapped air in tires).

Many problems have had to be overcome even after development of theabove higher strength filaments and cords. The higher strength steelalloys resulted in changes in cord modulus giving rise to thepossibility of adjusting the parameters of a tire belt gross load whichdepends upon three factors assuming adequate cord to rubber adhesion.The factors are cord modulus, the ratio of cord volume to rubber volume(often expressed as the number of cord ends per inch (epi)), and theangle of cord reinforcement. Further, as the angle of cord reinforcementapproaches the direction of rotation of the tire, the support from thereinforcement in the lateral direction moves toward zero. An increase inthe above-mentioned two other cord related factors, i.e., the cordmodulus and the ratio of cord volume to rubber volume, generally resultsin an increase of weight for the belt. Added weight can mean added cost,higher rolling resistance and lower fuel economy of a tire. Simply usinglighter cords with a lower modulus does not solve the problem because,even though they have lower weight, the lower cord modulus must beoffset by increasing the ratio of cord to rubber volume. This increasein cord volume is limited by the physical size of the cord and theresulting spacing between the cords which governs the amount of rivet,i.e., the ability of the rubber to penetrate between the cords for goodcord to rubber adhesion.

SUMMARY OF THE INVENTION

It is an object of the present invention to determine cord structureswhich could take advantage of a new cord modulus while not adverselyaffecting cord volume to rubber volume ratio on lateral reinforcement soas to obviate the problems and limitations of the prior art tires andcord constructions.

It is another object of the present invention to provide cord structuresusing ultra tensile wire which results in lighter weight tires.

It is still another object of the present invention to provide cordstructures using ultra tensile wire which results in tires with highercorrosion propagation resistance and more rivet leading to improved tireperformance.

The present invention relates to a cord for reinforcing elastomerarticles of multiple filaments having a diameter (D) ranging from 0.10to 0.45 mm, each filament having at least a tensile strength of−2000×D+4400 MPa, where D is the filament diameter. These cords areparticularly useful in a carcass ply and/or belt structure of apneumatic tire.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the cross section of a first embodiment of a tirehaving a composite structure including two plies according to thepresent invention;

FIG. 2 illustrates a partial cross section of a second embodiment of atire having a composite structure including four plies according to thepresent invention;

FIG. 3 shows the cross section through a cord in accordance with anembodiment of the present invention;

FIG. 4 is a schematic illustration in cross section of a composite, suchas two abutted plies, in accordance with the present invention; and

FIGS. 5 through 16 show the cross section through a cord in accordancewith different embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

There is disclosed a cord for reinforcing elastomer articles of multiplefilaments having a diameter (D) ranging from 0.10 to 0.45 mm, eachfilament having at least a tensile strength of −2000×D+4400 MPa, where Dis the filament diameter. These cords are particularly useful in acarcass ply and/or belt structure of a pneumatic tire.

There is also disclosed a pneumatic tire with a carcass having parallelcords, two sidewalls spaced apart a distance, which in the axialdirection determines the general width of the tire section, two beadseach one of which around which are turned up, from the inside toward theoutside, the ends of the cords of the carcass, a tread disposed on thecrown of said carcass, a belt structure that is circumferentiallyinextensible interposed between the tread and the carcass, and carcassplies disposed in said sidewalls between said two beads and said crownof said carcass, said belt structure having a width that issubstantially equal to that of the tread and having carcass plies ofelastomeric fabric reinforced with metallic cords, said metallic cordsbeing comprised of a plurality of filaments having a diameter (D)ranging from 0.10 to 0.45 mm, each filament having a tensile strength of−2000×D+4400 MPa, where D is the filament diameter.

In addition, there is disclosed a pneumatic tire with a carcass havingparallel cords, two sidewalls spaced apart a distance, which in theaxial direction determines the general width of the tire section, twobeads each one of which around which are turned up, from the insidetoward the outside, the ends of the cords of the carcass, a treaddisposed on the crown of said carcass, a belt structure that iscircumferentially inextensible interposed between the tread and thecarcass, and carcass plies disposed in said sidewalls between said twobeads and said crown of said carcass, said belt structure having a widththat is substantially equal to that of the tread and being constructedof at least one belt of elastomeric fabric reinforced with metalliccords, said metallic cords being comprised of a plurality of filamentshaving a diameter (D) ranging from 0.10 to 0.45 mm, each filament havinga tensile strength of −2000×D+4400 MPa, where D is the filamentdiameter.

After considerable study, effort, testing and time, the presentinvention provides cords and plies for passenger, light truck, truck,medium truck and OTR tires which substantially reduce the size andsometimes the number of filaments for the load ranges encompassed bythis range of tires. While the reduction in the number of filamentsleads one to expect a reduction in weight, this is not necessarily thecase since the prior art materials require that the filament size alsobe increased in order to obtain the needed strength for the tire.However, with the use of Ultra Tensile steel for the cord constructions,the number and/or the size of the filaments can be decreased whilemaintaining or even strengthening the tire. Under such circumstances,cord was found for use in the load ranges by varying the ends per inch(EPI) in the plies of the belt. Other advantages which exist in thepresent invention include lighter tires, improved rolling resistance,higher corrosion propagation resistance, and a reduction in the cordtreatment gauge between the cord layers in the belt. A weight reductiondue to a reduction in weight of reinforcement as well as a reduction inan amount of gum gauge also results in a reduction in manufacturing costand improved fuel economy for the tires of the present invention.Moreover, it is believed that improved temperature transfer can beachieved with the new cord designs of the invention to lengthen the lifeand improve the operating performance of tires incorporating thesecords. Further, the new belt structures give better rolling resistance,perhaps because of the lighter weight of the new cord designs ascompared with the old cord designs being used for reinforcement in thebelt structure.

As used herein and in the claims:

“Axial” and “axially” are used herein to refer to lines or directionsthat are parallel to the axis of rotation of the tire.

“Bead” means that part of the tire comprising an annular tensile memberwrapped by ply cords and shaped, with or without other reinforcementelements such as flippers, chippers, apexes, toe guards and chafers, tofit the design of the tire rim.

“Belt structure” means at least two layers or plies of parallel cords,woven or unwoven, underlying the tread, unanchored to the bead, andhaving both left and right cord angles in the range from about 17 toabout 70 degrees with respect to the equatorial plane (EP) of the tire.

“Carcass” means the tire structure apart from the belt structure, thetread, the undertread and the sidewall rubber over the plies, butincluding the beads.

“Cord” means one or more of the reinforcement elements, formed by two ormore filaments/wires which may or may not be twisted or otherwise formedand which may further include strands that may or may not be also soformed, of which the plies in the tire are comprised.

“Crown” means that portion of the tire within the width limits of thetire tread.

“Density” means weight per unit length.

“Equatorial plane (EP)” means the plane perpendicular to the tire's axisof rotation and passing through the center of the tire's tread.

“Gauge” means material thickness.

“High Tensile Steel (HT)” means a carbon steel with a tensile strengthof at least 3400 Mpa @ 0.20 mm filament diameter.

“Super Tensile Steel (ST)” means a carbon steel with a tensile strengthof at least 3650 Mpa @ 0.20 mm filament diameter.

“Ultra Tensile Steel (UT)” means a carbon steel with a tensile strengthof at least 4000 Mpa @ 0.20 mm filament diameter.

“Load Range” means load and inflation limits for a given tire used in aspecific type of service as defined by tables in The Tire and RimAssociation, Inc., 1989 Year Book.

“Radial” and “radially” are used to mean directions radiallyperpendicular from the axis of rotation through the tire.

“Rivet” means the open space between cords in a layer.

“Section width” means the maximum linear distance parallel to the axisof the tire and between the exterior of its sidewalls when and after ithas been inflated at normal pressure for 24 hours, but unloaded,excluding elevations of the sidewalls due to labeling, decoration orprotective bands.

“Stiffness ratio” means the value of the control belt structurestiffness divided into the value of another belt structure stiffnesswhen the values are determined by a fixed three (3) point bending testhaving both ends of the cord supported and flexed by a load centeredbetween the fixed ends.

The cords of the present invention may comprise of a number ofconstructions both with or without a spiral wrap. For example,representative constructions include 2×, 3×, 4×, 5×, 6×, 7×, 8×, 11×,12×, 27×, 1+2, 1+3, 1+4, 1+5, 1+6, 1+7, 1+8, 1+14, 1+15, 1+16, 1+17,1+18, 1+19, 1+20, 1+26, 2+2, 2+5, 2+6, 2+7, 2+8, 2+9, 2+10, 2/2, 2/3,2/4, 2/5, 2/6, 3+2, 3+3, 3+4, 3+6, 3+9, 3/9, 3+9+15, 4×4, 5/8/14, 7×2,7×3, 7×4, 7×7, 7×12 and 7×19. Representative cord constructions with aspiral wrap include 2+1, 3+1, 5+1, 6+1, 7+1, 8+1, 11+1, 12+1, 1+4+1,1+5+1, 1+6+1, 1/6+1, 1+7+1, 1+8+1, 1+14+1, 1+15+1, 1+16+1, 1+17+1,1+18+1, 1+19+1, 1+20+1, 1+26+1, 2+7+1, 2+8+1, 2+9+1, 2+10+1, 3+9+1,3/9+1, 3+9+15+1, 7×2+1, 7×12+1, 7×19+1 and 27+1.

The cords listed above are particularly suited for use in a pneumatictire. The pneumatic tire may be a bias or radial ply tire. When used inthe carcass ply, the preferred cords are 2×, 3×, 4×, 5×, 6×, 8×, 11×,12×, 1+2, 1+3, 1+4, 1+5, 1+6, 1+7, 1+8, 1+14, 1+15, 1+16, 1+17, 1+18,1+19, 1+20, 2+1, 2+7, 2+8, 2+9, 2+10, 2/2, 2/3, 2/4, 2/5, 2/6, 3+1, 3+2,3+3, 3+4, 3+9, 3/9, 3+9+15, 5/8/14, 7×12, 7×19, 5+1, 6+1, 7+1, 8+1,11+1, 12+1, 2+7+1, 1+4+1, 1+5+1, 1+6+1, 1+7+1, 1+8+1, 1+14+1, 1+15+1,1+16+1, 1+17+1, 1+18+1, 1+19+1, 1+20+1, 3+9+1, 3/9+1, 7×12+1 and 7×19+1.

When the cords of the present invention are used in a belt structure,the preferred cords are 2×, 3×, 4×, 5×, 6×, 8×, 11×, 12×, 1+2, 1+3, 1+4,1+5, 1+6, 1+7, 1+8, 1+14, 2+2, 2+5, 2+6, 2+7, 2+8, 2+9, 2+10, 2+2+8,2/2, 2/3, 2/4, 2/5, 2/6, 3+2, 3+3, 3+4, 3+6, 3+9, 3+9+15, 27×, 1+26,4×4, 5/8/14, 7×2, 12+1, 3+9+1, 1+6+1, 2+6+1, 2+7+1, 2+8+1, 2+9+1,2+10+1, 2+2+8+1, 3+9+15+1, 27+1, 1+26+1 and 7×2+1.

The filaments which may be used to make the cords of the presentinvention may have a diameter ranging from 0.10 mm to 0.45 mm.Preferably, the diameter of the filament ranges from 0.14 to 0.43 mm. Aparticularly preferred filament ranges from 0.18 to 0.38 mm.

According to the invention, a pneumatic off-the-road tire of 36 inch andgreater bead diameter with a carcass having cords, two sidewalls spacedapart a distance, which in the axial direction determines the generalwidth of the tire section, two beads around each one of which are turnedup the ends of the cords of the carcass, a tread disposed on the crownof the carcass, and a belt structure circumferentially disposed betweenthe tread and the carcass is disclosed. The belt structure has a widththat is substantially equal to that of the tread and has at least onelayer of elastomeric fabric reinforced with metallic cords. The metalliccords of the present invention are used in at least one layer such as a7×19×0.20+1 construction. In another embodiment, a pneumaticoff-the-road tire incorporates metallic cords of the present inventionin a 7×12×0.22+1 construction. In a third embodiment, a pneumaticoff-the-road tire incorporates metallic cords of the present inventionhaving a 7×12×0.25+1 construction.

There are a number of embodiments of metallic cord construction of thepresent invention for the plies including 1×0.18, 2×0.18, 3×0.18. Also,according to the invention, the cords of the ply can be constructed of1+5×0.18. The tire can also include a ply having a cord of1×0.24/6×0.22+1 or 1×0.18/6×0.16+1 construction.

According to the invention, the pneumatic radial tire described beforecan include a belt structure of elastomeric fabric reinforced withmetallic cords where the metallic cords are parallel to each andcomposed of filaments of ultra tensile steel. In one embodiment, thebelt structure includes first and second overlapped belts wherein thecords of the first and second belts are constructed of cords of thepresent invention having various configurations including, 2+2×0.30,2+2×0.35, 2×0.30, 2×0.35, 2+2×0.30, 2×0.23, 2×0.30, 3+2×0.33 and3+4×0.38.

In another embodiment of the former tire, the belt structure includesfirst, second, third and fourth radially overlapped belts wherein thecords of the present invention used in the first and fourth belt areconstructed of 3+2×0.33 and the cords of the present invention used ineach of the second and third belts, sandwiched between the first andfourth belts are constructed of 3+3×0.33. This tire also includes a plyhaving a cord of the present invention in a 3×0.22/9×0.20+1construction. In still another embodiment, the belt structure includesfirst, second, third and fourth radially overlapped belts wherein thecords of each of the present invention are used in each of the first andfourth belts are constructed of 3+4×0.38 and the ply has a cord of3×0.22/9×0.20+1.

Further, many of the above described novel cords result in lower lineardensity in the reinforcement for which they are used which again resultsin less weight and lower cost for the reinforcement and its product, beit the tire, the belt or any other reinforced elastomeric.

Referring to FIGS. 1 and 2 of the drawings, plies 12 and 14 are shownwithin a pneumatic tire 10 with a radial carcass wherein like elementshave received like reference numerals. For the purposes of the presentinvention, a tire has a radial ply carcass structure when the cords ofthe carcass reinforcing ply, or plies 12, 14 are oriented at angles inthe range of 75° to 90° with respect to the equatorial plane (EP) of thetire.

In the instance where the metallic cords of the present invention areused to reinforce the carcass, only one of the two plies, if two areused, should be so reinforced. The other ply should be reinforced withsome other form of reinforcement. It is preferred that, if two carcassplies are used, the metallic cord reinforced ply be the bottom (inner)carcass ply 14. Representative examples of reinforcement that can beused in the other non-metallic reinforced carcass ply is rayon,polyester and nylon.

The metallic cord reinforced carcass ply 12 has a layer of steel cords30 arranged so as to have from about 8 to about 20 ends per inch (EPI)when measured in a tire circumferential direction at a location having atire maximum width (MW). Preferably, the layer of steel cords 30 arearranged so as to have about 12 to about 16 ends per inch (EPI) at thelocation having a tire maximum width MW. In terms of metric units, thesteel cords are arranged as to have from 3 to 8 ends per cm (EPC) whenmeasured in a tire circumferential direction at a location having a tiremaximum width. Preferably, the EPC ranges from 4 to 7 EPI. The abovecalculations for ends per inch are based upon the range of diameters orthe overall cords, strength of the filaments and cords as well as therequired strength requirement for the single carcass ply. For example,the high number of ends per inch would include the use of a lowerdiameter wire for a given strength versus a lower number of ends perinch for a lower diameter wire for the same strength. In thealternative, if one elects to use a monofilament of a given diameter,one may have to use more or less ends per inch depending on the strengthof the wire.

The tire 10 has a pair of substantially inextensible annular beads 16,18 which are axially spaced apart from one another. Each of the beads16, 18 is located in a bead portion of the tire 10 which has exteriorsurfaces configured to be complimentary to the bead seats and retainingflanges of a rim (not shown) upon which the tire 10 is designed to bemounted. Plies 12, 14 may be of side-by-side reinforcing cords ofpolyester or other material, or steel cord of the present invention andextend between the beads 16, 18 with an axially outer portion of thecarcass structure folded about each of the beads. While in theembodiment of FIG. 1, the carcass ply structure comprises two plies 12,14 of reinforcing material, it is understood that one or more carcassplies of any suitable material may be employed in certain embodimentsand one or more plies of reinforcement according to this invention maybe used as well.

A layer of a low permeability material 20 may be disposed inwardly ofthe carcass plies 12, 14, and contiguous to an inflation chamber definedby the tire and rim assembly. Elastomeric sidewalls 22, 24 are disposedaxially outwardly of the carcass structure. A circumferentiallyextending belt structure 26 comprising in the embodiments shown twolayers of belts 28, 30 (FIG. 1), or four layers of belts 28, 30, 32, 34(FIG. 2), each of which preferably includes steel reinforcing cords 36as shown in FIG. 3. The belt structure 26 of FIG. 2 is characterized bythe cords 36 having filaments with a tensile strength of at least 4000MPA [N/mm²] (called “ultra tensile” herein) for filaments with a 0.20 mmdiameter. For example, cord 36, as shown in FIG. 3, has four filaments38, 40, 42 and 44 (38-44) of ultra tensile steel wire. While two andfour layer belts are illustrated in FIGS. 1 and 2, respectively, othernumbers of belts can be substituted.

It will be appreciated that other laminates can be formed usingprinciples of the present invention for reinforcing other articles suchas industrial belts and that a single ply of the present invention canbe used with known or conventional plies to also form new usefulreinforced composite structures.

In a working example, the cords 36 are comprised of four filaments 38-44of finely drawn, ultra tensile steel wire. There are a number ofmetallurgical embodiments which result in the tensile strength definedabove, i.e. at least 4000 MPA, as ultra tensile (UT). One way ofachieving UT strength is by merging the proper process as disclosed inU.S. Pat. No. 4,960,473, which is hereby incorporated by reference inits entirety herein, with a carbon rod microalloyed with one or more ofthe following elements: Cr, Si, Mn, Ni, Cu, V and B. The preferredchemistry is listed below:

C 0.88 to 1.0 Mn 0.30 to 0.50 Si 0.10 to 0.3 Cr 0.10 to 0.4 V 0 to 0.1Cu 0 to 0.5 Ni 0 to 0.5 Co 0.2 to 0.1 the balance being iron andresiduals

The resulting rod is then drawn to a tensile strength equivalent to 4000Mpa @ 0.20 mm.

TABLE 1 below gives calculated strength level description for ultratensile filaments in comparison to previous high and super tensile steelfilaments having a filament diameter of 0.20 mm. The ultra tensile steelhas a higher value than any previously used steel cord or filament.

TABLE 1 HIGH TENSILE, SUPER TENSILE & ULTRA TENSILE STEEL CORD StrengthLevel Description High Tensile Super Tensile (HT) (ST) Ultra TensileRating    100    107    117 Tensile Strength   3400   3650   4000 (MPa)for filament diameter (D) Tensile Strength −1400 × D −2000 × D −2000 × D(MPa) for filament +3680 +4050 +4400 diameter (D)

The cords 36 used in the working example, as shown in FIG. 3, have astructure of four filaments 38, 40, 42 and 44 typically of 0.30 mm or0.35 mm diameter ultra tensile steel wire with a cord breaking strengthof at least 1,020 Newtons, plus or minus 5.0 percent. Each cord 36 hastwo filaments 38, 40 twisted together with a 16 mm lay length and thesetwo filaments 38, 40 are then twisted at a 16 mm lay length together inthe same twist direction with the remaining two filaments 42, 44 whichare untwisted and parallel to each other when twisted together with thetwisted filaments 38, 40. This cord, commonly called a 2+2 constructionis designated as 2+2×0.30 UT or 2+2×0.35 UT. The 2+2 construction isknown for its openness and good rubber penetration resulting from theopenness. The 0.30 and 0.35 designates the filament diameter inmillimeters and the UT designates the material being ultra tensilesteel.

TABLE 2 Former Cord Structure Ultra Tensile Cord Structure Max Max CordGauge Cord Gauge Structure (mm) Structure (mm) Radial Passenger andLight Truck Belts 1) 2 × .30 HT .60 2 × .23 UT 0.46 Radial Light TruckBelts 2) 2 + 2 × .30 HT .90 2 × .30 UT 0.60 3) 2 + 2 × .30 HT .90 2 ×.35 UT 0.70 Radial Medium Truck Belts 4) 2 + 2 × .35 ST 1.05 2 + 2 × .30UT 0.90 1.05 2 + 2 × .33 UT 0.99 1.05 2 + 2 × .35 UT 1.05 5) 3 + 2 × .35ST 1.05 3 + 2 × .30 UT 0.90 1.05 3 + 2 × .33 UT 0.99 1.05 3 + 2 × .35 UT1.05 6) 3 + 3 × .35 ST 1.05 3 + 3 × .30 UT 0.90 1.05 3 + 3 × .33 UT 0.951.05 3 + 3 × .35 UT 1.05 7) N + M × DST¹ N + M × .30 UT 0.90 N + M × .33UT 0.95 N + M × .35 UT 1.05 ¹Where N is any number from 1-5 M is anynumber from 1-5 D is any diameter from 0.18 to 0.38 mm

Above in TABLE 2 are other embodiments of ultra tensile cord matched forcomparison with the former tire cord, e.g., high tensile (HT) and supertensile (ST) steel cords which it replaced, the above example cord 36being listed as 2 and 3. The illustrated examples of ultra tensile cordstructure, candidates 1 and candidates 2, 3 and 4 above in TABLE 2, areshown in FIGS. 5 and 3, respectively, and show a reduction in cord gaugeas compared with the corresponding former cord structures of the threecandidates. When the new cord structures incorporate filaments having asmaller diameter than those of the previously noted corresponding formercord structures, there is a resulting reduction in gauge material andcost as compared with the former cord structures making the tireslighter in weight and less costly.

For equal filament diameters, the ultra tensile cords have higherstrength and generally higher fatigue life over the predecessor high andsuper tensile cords. These advantages lead to elastomer products whichhave less reinforcement material and thus lower weight and cost.Further, the life of the product can be increased with the increase infatigue life of the cord and its filaments.

In a similar manner, the illustrated examples of ultra tensile cordstructure, candidates 5 and 6 above in TABLE 2, are shown in FIGS. 7 and8, respectively, and show a reduction in cord gauge as compared with thetwo mentioned corresponding former cord structures. Further, the newcord structures of small diameter filaments reduce gauge material andcost as compared with the previously noted former cord structures makingthe tires lighter in weight and less costly.

The following TABLE 3 shows other embodiments of ultra tensile plystructures matched for comparison with the former ply structures whichthey replace. Some former plies incorporate polyester or high tensile(HT) steel.

TABLE 3 Former Ply Structure Ultra Tensile Ply Structure Max Max CordCord Gauge Gauge Structure (mm) Structure (mm) Radial Passenger andLight Truck Plies 1) 1100/3 .66 2 × .18 UT .36 polyester single ply 2)1100/2 .56 3 × .18 UT .36 polyester two ply Radial Light Truck Plies 3)1440/3 .76 1 + 5 × .18 UT .54 polyester with and two ply without wrapRadial Medium Truck Belts 4) 27 × .175 HT 1.05 3 × .22/9 × .20 + 1 UT.84 5) 3 × .22/9 × .20 + .84 2 + 7 × .22 + 1 UT .88 1 HT 6) 3 × .22/9 ×.20 + .84 1 × .24 + 6 × .22 + 1 UT .68 1 HT 7) 3 × .22/9 × .20 + .84 1 ×.24 + 6 × .22 UT .68 1 HT Off-The-Road Plies 8) 7 × 19 × .20 + 1 HT 3.007 × 19 × .20 + 1 UT 3.00 9) 7 × 19 × .20 + 1 HT 3.00 7 × 12 × .22 + 1 UT2.34 10)  7 × 19 × .20 + 1 HT 3.00 7 × 12 × .25 + 1 UT 3.02

Candidates 1 and 2 above in TABLE 3 and illustrated in FIGS. 5 and 10,show a replacement of polyester ply with steel ply. The ply structuresincorporating UT steel filaments are stronger and reduce the gauge andcost of the material, as compared with the previously noted formerpolyester ply structures making the tires lighter in weight and lesscostly.

Candidate 3, above in TABLE 3, is related to radial light truck pliesand is illustrated in FIG. 11, shows a replacement of polyester ply withsteel ply.

Further, Candidates 4, 5, 6 and 7 above in TABLE 3, are related toradial medium truck plies and are illustrated in FIGS. 14, 12 and 13.These candidates show a replacement of high tensile ply configurationswith ultra tensile steel ply configurations. The ply structures of UTsteel filaments are stronger and reduce gauge material and cost ascompared with the previously noted former high tensile ply structuresmaking the tires lighter in weight and less costly.

Candidates 8, 9 and 10 above in TABLE 3, are related to off-the-roadplies as illustrated in FIGS. 15 and 16. These candidates show areplacement of a high tensile ply configuration, as shown in FIG. 15,with the corresponding ultra tensile steel ply configurations of FIGS.15 and 16. As in the previous cases, the ply structures of UT steelfilaments are stronger and reduce gauge material and cost as comparedwith the previously noted former high tensile ply structures making thetires lighter in weight and less costly.

TABLE 4 below compares the current construction together with a benefitanalysis of P195/75R14 passenger tires of two belts, as shown in FIG. 1and depicted in FIG. 4, wherein the current two layer belts incorporatehigh tensile cable configurations and the disclosed two layer belts ofthe new construction incorporate ultra tensile cable configurations.Three candidates of ultra tensile construction are described with (a)equal strength, lower tire gauge, higher EPI and lower tire weight incandidate 1; (b) equal strength, identical tire gauge, lower EPI andless tire weight in candidate 2; and (c) increased strength, equal tiregauge, equal EPI and equal tire weight in candidate 3.

With candidate 1, when the diameter of the filaments was decreased from0.30 mm high tensile to 0.23 mm ultra tensile, the EPI increased.Nevertheless, an equal strength was achieved with a lower tire gauge andsignificant savings in tire weight. With candidate 2, when the diameterof the filaments was held constant at 0.30 mm, the replacement of hightensile steel with ultra tensile steel resulted in a decrease in EPI anda lower weight tire of equal strength. With candidate 3, the replacementof high tensile steel with ultra tensile steel, while keeping the tiregauge and the EPI constant, resulted in a tire with the same weight andgauge, but with an approximate 16 percent increase in strength.

TABLE 4 ULTRA TENSILE STEEL CORD BENEFITS BELTS - PASSENGER TIRESP195/75R14 Current Ultra Tensile Belt Belt Structure StructureConstruction EPI Construction EPI Benefits 1) Belt 1 2 × .30 HT 24 2 ×.23 UT 34 Equal Strength     Belt 2 2 × .30 HT 24 2 × .23 UT 34 LowerTire Weight Gauge 0.096 in Gauge 0.080 in (0.5 lbs Weight 3.2 lbs Weight2.7 lbs lower) Lower Tire Gauge 2) Belt 1 2 × .30 HT 24 2 × .30 UT 20.5Equal Strength     Belt 2 2 × .30 HT 24 2 × .30 UT 20.5 Lower TireWeight Gauge 0.096 in Gauge 0.096 in (0.20 lbs Weight 3.2 lbs Weight 3.0lbs lower) 3) Belt 1 2 × .30 HT 24 2 × .30 UT 24 16% Increased     Belt2 2 × .30 HT 24 2 × .30 UT 24 Strength Gauge 0.096 in Gauge 0.096 inWeight 3.2 lbs Weight 3.2 lbs

TABLE 5 below compares the current construction together with a benefitanalysis of LT215/85R16 LR-C light truck tires of two belts, as shown inFIG. 1 and depicted in TABLE 5. The current belt structure incorporatestwo layered belts of 2+2 high tensile cable configurations and the newlydisclosed two layer belts incorporate ultra tensile cableconfigurations. Two candidates of ultra tensile construction with (a)equal strength, lower tire gauge, higher EPI and lower tire weight incandidate 1; and (b) equal strength, lower tire gauge, higher EPI andlower tire weight in candidate 2.

With candidate 1, the 2+2×0.30 HT configuration of Belt 1 was replacedwith a simpler 2×0.30 UT configuration and the 2+2×0.30 HT configurationof Belt 2 was replaced with a simpler 2×0.23 UT configuration. In eachcase, the EPI increased. Nevertheless, an equal strength was achievedwith a significant savings in tire weight and a lower tire gauge. Withcandidate 2, the 2+2×0.30 HT configurations of Belt 1 and Belt 2 wereeach replaced with a simpler 2×0.35 UT configuration. In each case, theEPI increased. Nevertheless, an equal strength was achieved with asignificant savings in tire weight and a lower tire gauge.

TABLE 5 ULTRA TENSILE STEEL CORD BENEFITS BELTS - RADIAL LIGHT TRUCKTIRES LT215/85R16 LR-C Current Belt Ultra Tensile Belt StructureStructure Construction EPI Construction EPI Benefits 1) Belt 1 2 + 2 ×.30 HT 13 2 × .30 UT 22 Equal Strength     Belt 2 2 + 2 × .30 HT 13 2 ×.30 UT 22 Lower Tire Weight Gauge 0.112 in Gauge 0.092 in (0.7 lbsWeight 4.8 lbs Weight 4.1 lbs lower) Lower Tire Gauge 2) Belt 1 2 + 2 ×.30 HT 13 2 × .35 UT 17 Equal Strength     Belt 2 2 + 2 × .30 HT 13 2 ×.35 UT 17 Lower Tire Weight Gauge 0.112 in Gauge 0.100 in (0.4 lbsWeight 4.8 lbs Weight 4.4 lbs lower) Lower Tire Gauge

Another comparison of high tensile and ultra-tensile cord is given inTABLE 5 where two current high tensile belt structures are compared withtwo candidates of ultra-tensile belt structures in LT215/85R1G LR-Cradial light truck tires. These tires incorporated two belts with 2+2type construction in the current models and a simple 2×0.30, 2×0.23 or2×0.35 cord in the ultra-tensile models. In construction 1, to achieveequal strength between the current high tensile and the ultra-tensileexamples, the EPI increased, the tire gauge was lower and a lower tireweight was achieved. In construction 2, the ultra-tensile filaments hada larger diameter and the EPI increased to maintain an equal strength.At the same time, both the tire gauge and the tire weight was lower.

TABLE 6 below compares the current construction together with a benefitanalysis of LT215/85R16 LR-D radial light truck tires of two belts, asshown in FIG. 1. The current belt structure incorporates two layeredbelts of 2+2 high tensile cable configurations and the newly disclosedtwo layered belts which incorporates ultra tensile cable configurations.Three candidates of ultra tensile construction with (a) equal strength,lower tire gauge, higher EPI and lower tire weight in candidate 1; (b)equal strength, equal tire gauge, lower EPI and lower tire weight incandidate 2; and (c) higher strength, equal tire gauge, equal EPI andequal tire weight in candidate 3.

With candidate 1, the 2+2×0.30 HT configuration of Belts 1 and 2 wereboth replaced with a simpler 2×0.35 UT configuration. In each case, theEPI increased. Nevertheless, an equal strength was achieved with asignificant savings in tire weight and a lower tire gauge. Withcandidate 2, the 2+2×0.30 HT configurations of Belt 1 and Belt 2 wereeach replaced with 2+2×0.30 UT configurations. In each case, the EPIdecreased while maintaining an equal strength, an equal tire gauge and areduction in tire weight. With candidate 3, the 2+2×0.30 HTconfigurations of Belt 1 and Belt 2 were again replaced with 2+2×0.30 UTconfigurations. However, in each case, the EPI remained the same. Theresult was a significantly increased strength, while the tire gauge andthe tire weight remained the same.

TABLE 6 ULTRA TENSILE STEEL CORD BENEFITS BELTS - RADIAL LIGHT TRUCKTIRES LT215/85R16 LR-D Current Ultra Tensile Belt Belt StructureStructure LR-D Construction EPI Construction EPI Benefits 1) Belt 1 2 +2 × .30 HT 17 2 × .35 UT 22 Equal Strength     Belt 2 2 + 2 × .30 HT 172 × .35 UT 22 Lower Tire Weight Gauge 0.112 in Gauge 0.100 in (0.4 lbsWeight 5.1 lbs Weight 4.7 lbs lower) Lower Tire Gauge 2) Belt 1 2 + 2 ×.30 HT 17 2 + 2 × .30 UT 14.5 Equal Strength     Belt 2 2 + 2 × .30 HT17 2 + 2 × .30 UT 14.5 Lower Tire Weight Gauge 0.112 in Gauge 0.112 in(.2 lbs Weight 5.1 lbs Weight 4.9 lbs lower) 3) Belt 1 2 + 2 × .30 HT 172 + 2 × .30 UT 17 16% Increased     Belt 2 2 + 2 × .30 HT 17 2 + 2 × .30UT 17 Strength Gauge 0.112 in Gauge 0.112 in Weight 5.1 lbs Weight 5.1lbs

TABLE 7 below compares the current construction together with a benefitanalysis of LT235/85R16 LR-E light truck tires of two belts, as shown inFIG. 1 and depicted in TABLE 7. The current belt structure incorporatestwo layered belts of 2+2 super tensile cable configurations and thenewly disclosed two layer belts incorporates ultra tensile cableconfigurations. Three candidates of ultra tensile construction with (a)equal strength, lower tire gauge, higher EPI and lower tire weight incandidate 1; (b) equal strength, equal tire gauge, lower EPI and lowertire weight in candidate 2; and (c) higher strength, equal tire gauge,equal EPI and equal tire weight in candidate 3.

With candidate 1, the 2+2×0.35 ST configuration of Belts 1 and 2 wereboth replaced with a 2+2×0.30 UT configuration. In each case, the EPIincreased. Nevertheless, an equal strength was achieved with asignificant savings in tire weight and a lower tire gauge. Withcandidate 2, the 2+2×0.35 HT configurations of Belt 1 and Belt 2 wereeach replaced with 2+2×0.35 UT configurations. In each case, the EPIdecreased while maintaining an equal strength, an equal tire gauge and areduction in tire weight. With candidate 3, the 2+2×0.35 STconfigurations of Belt 1 and Belt 2 were again replaced with 2+2×0.35 UTconfigurations. However, in each case, the EPI remained the same. Theresult was an increased strength, while the tire gauge and the tireweight remained the same.

TABLE 7 ULTRA TENSILE STEEL CORD BENEFITS BELTS - RADIAL LIGHT TRUCKTIRES LT235/85R16 LR-E Current Ultra Tensile Belt Belt StructureStructure LR-E Construction EPI Construction EPI Benefits 1) Belt 1 2 +2 × .35 ST 17.5 2 + 2 × .30 UT 21 Equal Strength     Belt 2 2 + 2 × .35ST 17.5 2 + 2 × .30 UT 21 Lower Tire Weight Gauge 0.126 in Gauge 0.114in (0.6 lbs Weight 7.2 lbs Weight 6.6 lbs lower) Lower Tire Gauge 2)Belt 1 2 + 2 × .35 ST 17.5 2 + 2 × .35 UT 16 Equal Strength     Belt 22 + 2 × .35 ST 17.5 2 + 2 × .35 UT 16 Lower Tire Weight Gauge 0.126 inGauge 0.126 in (0.3 lbs Weight 7.2 lbs Weight 6.9 lbs lower) 3) Belt 12 + 2 × .35 ST 17.5 2 + 2 × .35 UT 17.5 12% Increased     Belt 2 2 + 2 ×.35 ST 17.5 2 + 2 × .35 UT 17.5 Strength Gauge 0.126 in Gauge 0.126 inWeight 7.2 lbs Weight 7.2 lbs

TABLE 8 below compares a current two-ply P225/P75R15 passenger tire withan ultra tensile ply structure. With the candidate 1, equal strength wasachieved with lower tire gauge, an increase in EPI, and a slightincrease in weight. With candidate 2, equal strength was achieved withlower tire gauge, an equal EPI and a decrease in tire weight.

With candidate 1, the 1100/2 polyester configurations of Plies 1 and 2were replaced with 2×0.18 UT configuration. In this case, the EPIincreased while maintaining an equal strength, a lower tire gauge and alower tire weight. With candidate 2, the 1100/2 polyester configurationof Plies 1 and 2 were replaced with 3×0.18 UT configuration. In thiscase, the strength and EPI remained constant while achieving a lowertire gauge and a lower tire weight.

TABLE 8 ULTRA TENSILE STEEL CORD BENEFITS PLY - PASSENGER TIRESP225/75R15 Current Belt Ultra Tensile Belt Structure Structure Two-PlyConstruction EPI Construction EPI Benefits 1) Ply 1 1100/2 Poly 30 2 ×.18 UT 43 Equal Strength     Ply 2 1100/2 Poly 30 Lower Tire WeightGauge 0.084 in Gauge 0.044 in (.8 lbs Weight 3.4 lbs Weight 2.6 lbslower) Lower Tire Gauge 2) Ply 1 1100/2 Poly 30 3 × .18 UT 30 EqualStrength     Ply 2 1100/2 Poly 30 Lower Tire Weight Gauge 0.084 in Gauge0.044 in (.8 lbs Weight 3.4 lbs Weight 2.6 lbs lower) Lower Tire Gauge

TABLE 9 compares a current two-ply polyester construction with an ultratensile construction in LT235/85R16 radial light truck tires of a loadrange E. Referring to the candidate, an equal strength was maintainedwhile achieving lower tire weight and lower tire gauge. When the 1440/3polyester configuration of Plies 1 and 2 were replaced with 1+5×0.18 UTconfiguration, the EPI slightly increased, and an equal strength wasachieved with a reduction in tire weight and tire gauge.

TABLE 9 ULTRA TENSILE STEEL CORD BENEFITS PLY - RADIAL LIGHT TRUCK TIRESLT235/85R16 LR-E Current Belt Ultra Tensile Belt Structure StructureTwo-Ply Construction EPI Construction EPI Benefits 1) Ply 1 1440/3 Poly27 1 + 5 × .18 UT 28 Equal Strength     Ply 2 1440/3 Poly 27 Lower TireWeight Gauge 0.118 in Gauge 0.061 in (0.9 lbs Weight 6.6 lbs Weight 5.7lbs lower) Lower Tire Gauge

TABLE 10 below compares the current construction with a benefit analysisof 11R24.5 LR-G radial medium truck tires of four belts, as shown inFIG. 2. With candidate 1, the current belt structure includes fourlayered belts of 3+2 super tensile cable configurations and a ply of3×0.22/9×0.20+1 high tensile cable. The new disclosed four layer beltsand single ply incorporates a 3+2×0.33 ultra tensile for each of thebelts and a 1×0.24/6×0.22+1 UT for the ply. Note that the EPI of belts 1and 4, and belts 2 and 3 remain the same for both the current and newconstructions while the EPI for the new ply increases. The benefitsachieved by the use of the ultra tensile configurations is an increasein the rivet of belts 2 and 3, a tire weight reduction, a tire costreduction and improved corrosion resistance in the ply.

Referring to candidate 2, the belts of the current configurations werereplaced by belts with a 3+4×0.38 UT configuration and an EPI which islower than that in the current belts. The 3×0.22/9×0.20+1 HT cableconfiguration in the ply is replaced by a 1×0.24/6×0.22+1 UT cableconfiguration in the ply. The advantage of the configurations ofcandidate 2 is a significant increase in the rivet of belts 2 and 3, atire weight reduction, a tire cost reduction, improved corrosionresistance in the ply and single belt wire construction which isapplicable to all of the load ranges for the radial medium truck tires.

TABLE 10 ULTRA TENSILE STEEL BENEFITS RADIAL MEDIUM TRUCK TIRES 11R24.5LR-G Current Belt Ultra Tensile Belt Structure Structure ConstructionEPI Construction EPI Benefits 1) Belt 1 3 + 2 × .35 10 3 + 2 × .33 10Rivet increased ST UT 7% in belts 2 and 3. Belt 2 3 + 2 × .35 14 3 + 2 ×.33 14 Tire weight ST UT reduced by 2.8 lbs. Belt 3 3 + 2 × .35 14 3 + 2× .33 14 Tire cost ST UT reduced Belt 4 3 + 2 × .35 10 3 + 2 × .33 10Improved ST UT corrosion resistance in ply. Ply 3 × .22/ 16 1 × .24/ 209 × .20 + 1 6 × .22 + 1 HT UT 2) Belt 1 3 + 2 × .35 10 3 + 4 × .38 09Rivet increased ST UT 224% in belts 2 and 3. Belt 2 3 + 2 × .35 14 3 + 4× .38 09 Tire weight ST UT reduced by 0.7 lbs. Belt 3 3 + 2 × .35 14 3 +4 × .38 09 Tire cost ST UT reduced. Belt 4 3 + 2 × .35 10 3 + 4 × .38 09Improved ST UT corrosion resistance in ply. Ply 3 × .22/ 16 1 × .24/ 20One belt wire 9 × .20 + 1 6 × .22 + 1 construction HT UT applicable toall load ranges.

TABLE 11 below compares the current construction with a benefit analysisof 11R24.5 LR-H radial medium truck tires of four belts, as shown inFIG. 2. With candidate 1, the current belt structure includes fourlayered belts of 3+2 and 3+3 super tensile cable configurations and aply of 3/9/15×0.175+1 HT cable. The newly disclosed four layer belts andsingle ply incorporates a 3+2×0.33 UT for belts 1 and 4, a 3+3×0.33 UTfor belts 2 and 3 and a 3×0.22/9×0.20+1 UT for the ply. Note that theEPI of belts 1 and 4 and belts 2 and 3 remain the same for both thecurrent and new constructions while the EPI for the new ply constructionincreases. The benefits achieved by the use of the ultra tensileconfigurations is an increase in the rivet of belts 2 and 3, a tireweight reduction and a tire cost reduction.

Referring to candidate 2, the belts of the current configurations werereplaced by belts with a 3+4×0.38 UT configuration and an EPI which islower than that in the current belts. The 3/9/15×0.175+1 HT cableconfiguration in the ply is replaced by a 3×0.22/9×0.20+1 UT cableconfiguration in the ply. The advantage of the configurations ofcandidate 2 is a significant increase in the rivet of belts 2 and 3, atire weight reduction, a tire cost reduction and single belt wireconstruction which is applicable to all of the load ranges for theradial medium truck tires.

TABLE 11 ULTRA TENSILE STEEL BENEFITS RADIAL MEDIUM TRUCK TIRES 11R24.5LR-H Current Belt Ultra Tensile Belt Structure Structure ConstructionEPI Construction EPI Benefits 1) Belt 1 3 + 2 × .35 10 3 + 2 × .33 10Rivet increased ST UT 10% in belts 2 and 3. Belt 2 3 + 3 × .35 16 3 + 3× .33 16 Tire weight ST UT reduced by 2.9 lbs. Belt 3 3 + 3 × .35 16 3 +3 × .33 16 Tire cost ST UT reduced. Belt 4 3 + 2 × .35 10 3 + 2 × .33 10ST UT Ply 3/9/ 13 3 × .22/ 19 15 × .175 + 9 × .20 + 1 1 HT UT 2) Belt 13 + 2 × .35 10 3 + 4 × .38 09 Rivet increased ST UT 225% in belts 2 and3. Belt 2 3 + 3 × .35 16 3 + 4 × .38 11 Tire weight ST UT reduced by 1.6lbs. Belt 3 3 + 3 × .35 16 3 + 4 × .38 11 Tire cost ST UT reduced. Belt4 3 + 2 × .35 10 3 + 4 × .38 09 One belt wire ST UT constructionapplicable to all load ranges. Ply 3/9/ 13 3 × .22/ 19 15 × .175 + 9 ×.20 + 1 1 HT UT

By utilizing ultra tensile steel filament of at least 4000 MPa at a 0.20mm diameter, several options become available in steel cord design forOff-The-Road (OTR) pneumatic tires, as described in TABLE 12 below.Utilization of the higher tensile strength materials combined withsimplification and/or variations of current steel cord construction willsatisfy the OTR tire requirements of higher inch strength whileincreasing the rivet area between cords. For example, the steel cordcable construction currently used for ply reinforcement in OTR tires forsizes 36.00R51 and larger is 7×19×0.20+1 HT, as shown in TABLES 3 and13. The filament tensile strength is specified as 3300 MPa at 0.20 mmfilament diameter. The average cable breaking load is 11,600 N and isused at 6.4 ends/inch thus giving an inch strength of 74,240 N whichsatisfies the design requirement of 73,975 N. The cable gauge of 3.0 mmyields a rivet of 0.965 mm.

A major design parameter which may be varied in a reinforced compositeof elastomer is the end count in end per inch (EPI), i.e., the number ofcords per unit length in the lateral direction to the direction in whichthe elastomer is being reinforced. TABLE 12 below lists examples of acurrent high tensile construction and possible ultra tensileconstructions, see candidates 1-3 and FIGS. 15 and 16, showing thegeneral increase in rivet as the increased strength of the ultra tensilesamples allowed a reduction in EPI. At the other extreme, as corddiameter is reduced and the end count increased to off-set it, the rivetis reduced. Generally, a minimum rivet of 0.018″ (0.46 mm) must bemaintained to give proper penetration of elastomers between cords whenthey are so embedded. This minimum rivet is particularly obtainable withthe smaller diameter and simpler (less filaments in a cord) cordconstruction of candidates 1, 2 and 3.

TABLE 13 Break Inch- Gauge Load Stretch Rivet Construction (mm) (N) EPI(N) (mm) Current Construction 7 × 19 × .20 + 1 3.0  11,600 6.4 74,240.965 HT Ultra Tensile Construction 1. 7 × 19 × .20 + 3.0  13,570 5.574,630 1.62 1 UT 2. 7 × 12 × .22 + 2.34 10,500 7.1 74,550 1.24 1 UT 3. 7× 12 × .25 + 3.02 13,000 5.7 74,100 1.44 1 UT

Candidates 1, 2 and 3 satisfy the tire design requirements of 74,240 Ninch-strength for 36.00R51 through 40.00R57 OTR tires while providingincreased rivet in all cases (greater than 0.96 mm). This increasedrivet allows more rubber penetration between cords giving greaterstrike-through. In addition, candidate 1, when used at 6.4 EPI (notshown), has a rivet area between cords of 0.965 mm (as with the currentconstruction) while providing an inch-strength of 83,200 N. This valueof inch-strength exceeds the requirement of 79,800 N/inch for a new,larger 44.00R57 OTR tire.

It is apparent that there has been provided, in accordance with thisinvention, a strip of ply stock reinforced with steel monofilaments orcords for use in a tire. The strip of reinforced, ply stock satisfiesthe objects, means and advantages set forth hereinbefore.

While the invention has been described in combination with embodimentsthereof, it is evident that many alternatives, modifications andvariations will be apparent to those skilled in the art in light of theforegoing description. Accordingly, it is intended to embrace all suchalternatives, modifications and variations as fall within the spirit andscope of the appended claims.

What is claimed is:
 1. A pneumatic tire with a carcass having parallelcords, two sidewalls spaced apart a distance, which in the axialdirection determines the general width of the tire section, two beadseach one of which around which are turned up, from the inside toward theoutside, the ends of the cords of the carcass, a tread disposed on thecrown of said carcass, a belt structure that is circumferentiallyinextensible interposed between the tread and the carcass, and carcassplies disposed in said sidewalls between said two beads and said crownof said carcass, said belt structure having a width that issubstantially equal to that of the tread and having carcass plies ofelastomeric fabric reinforced with metallic cords, said metallic cordshaving at least a two-layer construction wherein said cord constructionis 1+6, and being comprised of a plurality of filaments having adiameter (D) ranging from 0.18 to 0.38 mm, each filament having atensile strength of at least −2000×D+4400 MPa, where D is the filamentdiameter in mm.
 2. The pneumatic tire of claim 1 wherein the metalliccords are steel cords arranged so as to have from about 8 to 20 ends perinch when measured in a tire circumferential direction at a locationhaving a tire maximum width.